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/* $Id: avx_sig.c,v 1.12 2021/12/11 22:47:09 kostik Exp $ */
/*
* Naive test to check that context switches and signal delivery do
* not corrupt AVX registers file (%xmm). Run until some
* inconsistency detected, then aborts.
*
* FreeBSD:
* ${CC} -Wall -Wextra -O -g -o avx_sig avx_sig.c -lpthread
* Linux
* ${CC} -D_GNU_SOURCE -Wall -Wextra -O -g -o avx_sig avx_sig.c -lbsd -lpthread
*/
#include <sys/param.h>
#include <sys/time.h>
#include <sys/resource.h>
#include <sys/syscall.h>
#include <errno.h>
#include <pthread.h>
#ifdef __FreeBSD__
#include <pthread_np.h>
#endif
#ifdef __linux__
#include <bsd/stdlib.h>
#endif
#include <signal.h>
#include <stdatomic.h>
#include <stdbool.h>
#include <stdint.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#ifndef __unused
#define __unused __attribute__((__unused__))
#endif
#ifndef nitems
#define nitems(x) (sizeof((x)) / sizeof((x)[0]))
#endif
struct xmmreg {
uint8_t xmm_bytes[16];
};
struct xmm {
struct xmmreg xmmreg[16];
};
#define X2C(r) asm("movdqu %0, %%xmm" #r : "=m" (xmm->xmmreg[r]))
#define C2X(r) asm("movdqu %%xmm" #r ", %0" : : "m" (xmm->xmmreg[r]) : "xmm" #r)
static void
cpu_to_xmm(struct xmm *xmm)
{
C2X(0); C2X(1); C2X(2); C2X(3); C2X(4); C2X(5); C2X(6); C2X(7);
C2X(8); C2X(9); C2X(10); C2X(11); C2X(12); C2X(13); C2X(14); C2X(15);
}
static void
xmm_to_cpu(struct xmm *xmm)
{
X2C(0); X2C(1); X2C(2); X2C(3); X2C(4); X2C(5); X2C(6); X2C(7);
X2C(8); X2C(9); X2C(10); X2C(11); X2C(12); X2C(13); X2C(14); X2C(15);
}
#undef C2X
#undef X2C
static atomic_uint sigs;
static void
sigusr1_handler(int sig __unused, siginfo_t *si __unused, void *m __unused)
{
atomic_fetch_add_explicit(&sigs, 1, memory_order_relaxed);
}
#ifdef SIGINFO
static void
siginfo_handler(int sig __unused)
{
struct rusage r;
if (getrusage(RUSAGE_SELF, &r) == 0) {
printf("%lu vctx %lu nvctx %lu nsigs ",
r.ru_nvcsw, r.ru_nivcsw, r.ru_nsignals);
}
printf("%u SIGUSR1\n", sigs);
}
#endif
static struct xmm zero_xmm = {};
static void
fill_xmm(struct xmm *xmm)
{
arc4random_buf(xmm, sizeof(*xmm));
}
static void
dump_xmm(const struct xmmreg *r)
{
unsigned k;
for (k = 0; k < nitems(r->xmm_bytes); k++) {
if (k != 0)
printf(" ");
printf("%02x", r->xmm_bytes[k]);
}
printf("\n");
}
static pthread_mutex_t show_lock;
static void
show_diff(const struct xmm *xmm1, const struct xmm *xmm2)
{
const struct xmmreg *r1, *r2;
unsigned i, j;
#if defined(__FreeBSD__)
printf("thr %d\n", pthread_getthreadid_np());
#elif defined(__linux__)
printf("thr %ld\n", syscall(SYS_gettid));
#endif
for (i = 0; i < nitems(xmm1->xmmreg); i++) {
r1 = &xmm1->xmmreg[i];
r2 = &xmm2->xmmreg[i];
for (j = 0; j < nitems(r1->xmm_bytes); j++) {
if (r1->xmm_bytes[j] != r2->xmm_bytes[j]) {
printf("xmm%u\n", i);
dump_xmm(r1);
dump_xmm(r2);
break;
}
}
}
}
static void
my_pause(void)
{
usleep(0);
}
static void *
worker_thread(void *arg __unused)
{
struct xmm xmm, xmm_cpu;
fill_xmm(&xmm);
for (;;) {
xmm_to_cpu(&xmm);
my_pause();
cpu_to_xmm(&xmm_cpu);
if (memcmp(&xmm, &xmm_cpu, sizeof(struct xmm)) != 0) {
pthread_mutex_lock(&show_lock);
show_diff(&xmm, &xmm_cpu);
abort();
pthread_mutex_unlock(&show_lock);
}
xmm_to_cpu(&zero_xmm);
my_pause();
cpu_to_xmm(&xmm_cpu);
if (memcmp(&zero_xmm, &xmm_cpu, sizeof(struct xmm)) != 0) {
pthread_mutex_lock(&show_lock);
show_diff(&zero_xmm, &xmm_cpu);
abort();
pthread_mutex_unlock(&show_lock);
}
}
return (NULL);
}
int
main(void)
{
struct sigaction sa;
int error, i, ncpu;
#ifdef SIGINFO
bzero(&sa, sizeof(sa));
sa.sa_handler = siginfo_handler;
if (sigaction(SIGINFO, &sa, NULL) == -1) {
fprintf(stderr, "sigaction SIGINFO %s\n", strerror(errno));
exit(1);
}
#endif
bzero(&sa, sizeof(sa));
sa.sa_sigaction = sigusr1_handler;
sa.sa_flags = SA_SIGINFO;
if (sigaction(SIGUSR1, &sa, NULL) == -1) {
fprintf(stderr, "sigaction SIGUSR1 %s\n", strerror(errno));
exit(1);
}
error = pthread_mutex_init(&show_lock, NULL);
if (error != 0) {
fprintf(stderr, "pthread_mutex_init %s\n", strerror(error));
exit(1);
}
ncpu = sysconf(_SC_NPROCESSORS_ONLN);
ncpu *= 2;
pthread_t wt[ncpu];
for (i = 0; i < ncpu; i++) {
error = pthread_create(&wt[i], NULL, worker_thread, NULL);
if (error != 0) {
fprintf(stderr, "pthread_create %s\n", strerror(error));
}
}
for (;;) {
for (i = 0; i < ncpu; i++) {
my_pause();
pthread_kill(wt[i], SIGUSR1);
}
}
}